But the really interesting – and in the long-term important –
sensor in the iPhone 5S is the M7, a “motion co-processor”
which allows it to measure data from the accelerometer, gyroscope
and compass without draining the battery as heavily as would be
required if the A7 processor were used. Effectively, using the
CoreMotion API, apps can access data about movement all day,
without destroying the battery life.

Think about that for a second. Your phone can now measure
everything that the likes of a Jawbone Up or Nike Fuelband
can. Plus, it can do it all day, with the processing power of
a 64bit computer to crunch that data when it needs it. And
that power is available to developers, to create applications
which single-purpose devices like the Fuelband will never be
able to match.

Seems like the sort of chip that could fit into a lot of other products, too.